Electrical circuit monitoring device

ABSTRACT

The present invention is directed to a method of (1) providing continuous monitoring of various operating and environmental characteristics using RFID technology or similar wireless technology and (2) capturing data on historical events that have occurred on the circuits used for the transmission and distribution of electric power. The invention has the additional capability to communicate the information to operators at the site, in remote locations, or to other equipment (peer to peer). The invention provides a low cost method and apparatus to monitor and store operating characteristics and events on the electric power distribution circuit. The information can be used to reduce the duration of outages, for improving system reliability, to study the impact on the power grid of various environmental factors, to enhance the ability to react to operating conditions such as overloads, etc.

RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.11/173,294, filed Jun. 30, 2005 now U.S. Pat. No. 7,295,133 that claimspriority from U.S. Provisional Patent Application No. 60/640,280, filedDec. 30, 2004.

BACKGROUND OF THE INVENTION

1. Field of Invention

This invention finds use in the field of the transmission anddistribution of electric power. In particular, this invention relates tothe application of RFID or similar wireless technology to monitoroperating characteristics and/or capture historical parametric dataabout events that have occurred on the power circuit.

2. Background

Systems have been developed and are currently in use to indicate theoperating characteristics of a power distribution circuit. Examples andsome of their limitations include:

-   -   Voltmeters and clamp on ammeters used by field crews to measure        voltage and current. These devices are usually used in        troubleshooting and are not designed for continuous real time        monitoring of operating characteristics. This equipment also        requires that an employee bring the device to the site and        connect it to the circuit in order to capture the information.    -   Faulted circuit indicators have also found wide application to        identify if a fault has occurred on the system. These devices        are left on the circuit but usually provide only a yes or no        identification of a faulted circuit event. Parameters such as        time of occurrence, fault direction, fault magnitude, etc are        not available. In addition, many of these devices are battery        operated and, as such, require periodic maintenance or have a        shortened useful lifetime after which they are replaced.    -   System Control & Data Acquisition (SCADA) Systems utilize a        personal computer (PC) or a mainframe computer to monitor        characteristics in real time. SCADA systems have the capability        to perform many of the improvements captured with this        invention. They are however quite expensive per monitored point        and, because of this currently find limited use only in the most        critical portions of the power distribution circuit such as        substations. In addition, these types of systems require that        ancillary, expensive data acquisition equipment such as a        current transformers, voltage transducers, and phase angle        transducers be hard wired into the circuit in order to capture        information.    -   Additionally, systems employing the technology can allow        autonomous control operation of certain switching and switch        closing/opening functions in a distributed fashion rather than        the centralized fashion of present SCADA systems.

SUMMARY OF INVENTION

The present invention is directed to a new class of devices that rely onRFID or similar wireless technology in a small relatively inexpensivepackage to provide the ability to:

-   -   (1) Continuously monitor a wide array of operating        characteristics on the electric power transmission or        distribution circuit in real time.    -   (2) Capture specific characteristics of an event on the circuit        and store the data for later retrieval.    -   (3) Communicate its “knowledge” to an individual on the ground        for data storage and later retrieval or to someone at a remote        location.    -   (4) Change the parameters being monitored without having to        rewire, reconfigure, or add additional measurement devices to        the power distribution circuit.    -   (5) Operate on the system without the need for a battery and be        installed independently or, with minor modification, in        equipment currently in use on the power circuit. Examples where        the invention may be added to a device to provide monitoring and        data collection activities include bushings, insulators, elbow        connectors, splices, transformers, switches, etc.

BRIEF DESCRIPTION OF THE DRAWINGS

Specific embodiments of the invention have been chosen for purposes ofillustration and description, and are shown in the accompanying drawing,forming a part of the specification wherein:

FIG. 1 is a perspective view of an insulator according to the invention;

FIG. 2 is a perspective view of the movable jaw portion of the insulatoraccording to the invention; and

FIG. 3 is circuit block diagram illustrating the micro-controller unitaccording to the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

The improved smart insulator according to the present invention will bedescribed herein by reference to the accompanying drawings. Referringnow to FIG. 1 the inventive smart insulator 10 is generally comprised ofan insulator portion 20, as is known and used in the art, and a movablejaw assembly 30. The insulator portion 20 prevents phase to phase powerline short circuits or phase to ground short circuits and is preferablyof a high voltage polymer style of the 15, 25 or 35 Kv class ofinsulators, although other materials that are or may be used in the art,such as porcelain, may be used. The movable jaw assembly 30 secures thepower line conductor (not shown) to the insulator. Mounting of theinsulator on a supporting structure, such as a pole, is well documentedin the art and apparent to those similarly skilled.

The movable jaw assembly 30 and insulator 20 are slideably engaged andsecured by eye-bolts 50, the rotation of which opens and closes the jawassembly 30. FIG. 2 illustrates an isolated view of the movable jaw 30.Jaw portion 30 serves as the housing for the current sensor 42,conductor temperature sensor 44, antenna 46, and microcontroller unit(“MCU”) 60, having an analog to digital converter 82. The jaw assembly30 may also contain other ancillary parametric measurement equipment.These and other sensors may take the form of transducers.

FIG. 3 schematically illustrates microcontroller unit 60 coupled toantenna 46. As is described in further detail, below, radio frequency(“rf”) energy is received by antenna 46 is coupled through transformer62 and rectified by diode 64 to charge super capacitor (super cap) 66.Power is coupled electrically 68 to the specific elements ofmicrocontroller 60 (as further detailed herein). Microcontroller unit 60can be preferably operated through energy received from the power line.Power line energy is picked up by coil 70 and rectified by diode 72,charging super cap 66. In this preferred embodiment, normal power issupplied by the power line through coil 70. When no line power isavailable to the MCU 60, the super cap 66 allows normal operations(namely receipt and storage of data) until the super cap loses itsstored energy. As is contemplated as part of the described invention anddescribed above, the super cap 66 can be charged by received rf energytransmitted by a remote data collection device that allows the MCU 60 tobe queried for data, particularly for event data that may be related toline power loss.

The microcontroller unit 60 has several associated subunits, namely aprogrammable gain element (“PGA”) 80, an analog to digital converter(“ADC”) 82, a central processing unit (“CPU”) 84, random access memory(“RAM”) 86, electronically alterable programmable read only memory(“EEPROM”) 88, an input/output section 90, a transmitting element ormeans (TX) 92 and a receiver element or means (RX) 94. Analog sensorinputs 96 (four are shown here) are signal conditioned by the PGA 80 anddigitized by the ADC 82, such that the digitized data represents ascaled value of the magnitude of the inputs. In the preferred embodimentof the invention, analog sensor inputs 96 are voltage field sensors,current sensors (such as sensor 42), temperature sensors (such as sensor44) and strain sensors. The recitation of such specific sensor types isnot meant to limit the invention as other sensor types known in the artmay used. Once the CPU 84 stores the received data in RAM 86, the valuesas compared at a periodic rate to determine if the data falls outside ofthe stored data values in the EEPROM 88, such that an alarm conditionmay occur. It is contemplated, and in fact preferred, that the CPU havea real time clock and calendar, or be electrically connected the same,to time and date stamp relevant event data. It should also be noted thatdata for voltage and current are preferably sampled at a rate thatpermits 32 samples of each cycle of the AC voltage and AC current, thuspermitting a representation of the waveform of the AC current andvoltage.

When a remote radio frequency command or query is detected by thereceiver element 94 (by way of antenna 46), it is decoded by the CPU 84and, depending on the command value, will initiate one of a set ofactions. One possible result is that the CPU 84 will transmit internaldata stored in RAM 86 via the transmitter element 92 for receipt by aremote receiver or to another inventive smart insulator 10. In thisinstance, another command value received by the receiver element 94initiates a transfer of data and commands from one smart insulator toanother such that peer-to-peer communications are permitted. Eachinventive insulator 10 has stored in EEPROM 88 a unique identifier suchthat data on one or more insulator can be passed backward or forwardfrom one insulator to another and, consequently, through a contiguouschain of insulators. One advantage of this ability to pass informationfrom one insulator to the next is that line/insulator status at aparticular insulator can be obtained at a base office or other remotelocation, rather than having access the insulator at its actuallocation. Similarly, it is also contemplated that the inventive smartinsulator 10 may also send commands to a receiver connected to a highvoltage power line switch which would perform the function of switchinga power factor correcting capacitor or capacitors on single or multiplephases of the power grid for the purpose of supporting the line powerfactor or power line voltage improvement.

Data, such as the parameters of the fault and the command value will bepreferably stored in non-static memory in addition to possibletransmission.

Those skilled in the art will notice that the technology of theinventive smart insulator is related to radio frequency identificationor RFID technology, but contains important differences. As such, a briefoverview of the current state of RFID technology is warranted.

RFID systems are generally not new technology, having its origins in theanti-theft/theft prevention and inventory tracking and access control.Originally, such technology was based on electromagnetic (EM) fielddetection. Detection based on EM fields was limited to only a viewinches with no data read-back capability. Such tags were also passive inthat they did not have any active circuitry and no battery depletionissues to consider. Next, the technology moved to RFID systems. The userbenefit was still passive, but had up to 42 inch read differences.Present technology RFID tags fall into two categories—passive smart tagsand active smart tags.

Passive smart (PS) RFID tags incorporate a microchip with onboardstorage capability of up to 64 bits for write once, ready manyoperations and are programmed at the time of use. The PS tags have theadvantage of battery-less use as the tag will “wake-up” and respond onlywhen queried by a reader. The RF energy contained in the wake-up query(or ping) supplies the tag with just enough power to send data back.Read distances are still fairly low—around 10 meters.

Active smart (AS) RFID tags differ from PS tags in that they contain abattery to maintain microchip data integrity, have a read range of about85 meters, the data is read/write and can be up to 256 k bits. The useof a battery and associated issues (5 year lifespan, heat and cold),limit the use of AS tags to applications such as monitoring movement ofhigh value assets, secure access control, and employee badgeidentification.

As can be appreciated, the technology of the instant invention offersdistinct advantages of over current PS and AS RFID technology including,but not limited to, wireless commutation ability between the respectivedevices, the ability to operate on multiple power sources, the abilityto provide a greater than instant charge to the device, and the abilityto continually write data to the device during use.

The technology disclosed herein is not confined solely to the previouslyrecited uses within an insulator. For example, the inventive technologycan be used for:

-   -   Power outage reporting/monitoring.    -   Telephone/cable line reporting and monitoring.    -   Multi-phase capacitor controls.    -   Fault sensing and automatic sectionalizing power-line switches,        including isolating a portion or section of a power line or grid        to isolate an area with a fault such that power may be restored        to the section before the faulted portion, and the faulted        portion isolated and disconnected in an automated fashion.    -   SCADA (Supervisory Control and Data Acquisition) peer to peer        monitoring points.    -   Micro weather alert stations (storm/lightning warnings).    -   DOT roadside monitors/alert stations.    -   Traffic control and monitoring.    -   Wireless line-post current sensors.        It also contemplated and expected that other components in the        electrical transmission grid, such as capacitor controls,        switches, spacers URD elbows, and streetlight controls, can use        such technology and, as such, the disclosed invention is not        limited to use in insulators only in the electrical transmission        field. It is further contemplated that many of the aspects of        the disclosed invention, such as use of rf energy to charge the        super capacitor and the use of wireless communications between        smart devices, have applications outside of the electrical        transmission field.

In summary, the inventive smart insulator has the many advantages overthe prior art including, but not limited to:

-   -   1. Prior art insulators, particularly those for 15, 25 and 35        Kv, have not had embedded micro-controller based data collection        monitoring capabilities, let alone with the ability to operate        with power line or battery energy;    -   2. Insulators have not had wireless communications capabilities;    -   3. Insulators have not had self-checking capabilities;    -   4. Insulators have not functioned as faulted circuit monitors;    -   5. Faulted circuit indicators have not recorded the fault        current and normal current magnitudes nor the fault or voltage        waveform for later remote retrieval via wireless communications;        and    -   6. Prior insulators and fault circuit indicators have not had        the ability to wirelessly communicate data from one insulator to        another or through a chain of such insulators to a monitoring        location.

In addition to the structures, sequences, and uses immediately describedabove, it will be apparent to those skilled in the art that othermodifications and variations can be made the method of the instantinvention without diverging from the scope, spirit, or teaching of theinvention. Therefore, it is the intention of the inventor that thedescription of instant invention should be considered illustrative andthe invention is to be limited only as specified in the claims andequivalents thereto.

1. A method of monitoring parametric data in a power distributionnetwork, the method comprising: a) providing at least one remotemonitoring node including at least one programmable radio frequencyidentification (RFID) device, the remote monitoring node comprising aninsulator portion and a jaw portion that houses the at least oneprogrammable radio frequency identification (RFID) device; providing atleast one high voltage insulator coupled to said electrical conductor,said insulator comprising an insulator portion and a jaw portion, saidjaw portion including a microcontroller, an antenna coupled to saidmicrocontroller, and at least one sensor coupled to a microcontroller b)obtaining parametric data from said power distribution network; c)inputting said parametric data into the at least one monitoring node; d)storing said parametric data on the at least one programmable RFIDdevice; e) querying said at least one programmable RFID device for saidparametric data.
 2. The method of claim 1 further comprising the step ofcomparing said parametric data to a preset baseline data and generatinga fault indicator status condition of said parametric data falls outsidesaid preset baseline data, storing said fault indicator status conditionon the at least one programmable RFID device and querying said at leastone programmable RFID device for said parametric data and fault indictorstatus condition.
 3. The method of claim 2 wherein the step of queryingsaid parametric data and said fault indictor status comprisestransmitting said data and indicator status from said RFID to anexternal receiver.
 4. The method of claim 1 further comprising the stepsof a) providing at least one analog sensor on said remote monitoringnode for obtaining parametric data; and b) comparing any parametric datagathered by any of the at least one analog sensors to baseline data toprovide an indication of an out of range fault.
 5. The method of claim 4whereby said baseline data is stored in computer memory.
 6. The methodof claim 1 wherein said parametric data includes data selected from thegroup consisting of tampering, intrusion and alarming conditions.
 7. Themethod of claim 4, wherein the at least one analog sensor is selectedfrom the group consisting of voltage field sensors, current sensors,temperature sensors, and strain sensors.
 8. The method of claim 7,wherein the parametric data comprises a waveform representation of ACcurrent or voltage.
 9. The method of claim 1, wherein the step ofstoring includes providing a time and date stamp to the parametric data.